Traditional spring mattresses generally contain an innerspring assembly having a set of springs that provide cushioning support to one or more users. When a user sleeps on the surface of the mattress, he/she applies a weight on the underlying springs, which in turn compress to provide adequate cushioning support. Typically, lighter users apply less weight on the springs, causing these springs to compress less and thereby providing a different feel to what a heavier person would experience. Consequently, lighter users might experience a different level of comfort as compared to heavier users for a given set of springs. This may present a problem when two sleeping partners are of significantly different weights, for example 120 lbs and 220 lbs. In such cases, one mattress is unlikely to be comfortable for both partners.
One reason that a traditional mattress may be more comfortable to certain users is that they are often constructed with springs having a linear spring rates. Such springs compress a distance that is linearly proportional to the weight of the user, until they reach full compression. Therefore springs may compress less under a light person than under a heavy person. Engineers have attempted to work around this problem by making mattress having springs with non-linear spring rates (e.g., conical springs). Such non-linear springs may compress significantly under a light person and yet not fully compress under a heavy person, occasionally providing similar levels of comfort for both. However, even non-linear springs such as conical springs are disadvantageous because of certain properties and general irregular shape. In particular, below a certain weight threshold, these springs still compress linearly with the weight applied. Non-linear type compression typically occurs beyond this weight threshold. Therefore, typical non-linear springs would have to significantly compress prior to a user experiencing a desired level of comfort. In other words, users would have to be of sufficient weight before they can experience a certain level of comfort provided by the springs' non-linear compression. Besides the disadvantage of requiring a heavy user, such significant compression of the innerspring assembly can also be unsuitable for the life of the bed. Moreover, mattresses having non-linear springs are difficult to manufacture because of the irregular shape of the spring coils. For example, conical springs are particularly difficult to assemble because they can not be in contact throughout their length as is called for in some methods of mattress assembly.
Accordingly, there is a need for a mattress that is comfortable for users with a broad range of weights. Generally, there is a need for a cushioning article that provides a similar level of cushioning support for a wide range of users.